ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: A γ-aminobutyric acidA (GABAA) receptor (GABAAR) γ2 subunit (short form) was cloned from an adult human cerebral cortex cDNA library in bacteriophage λgt11. The 261-bp intracellular loop (IL) located between M3 and M4 was amplified using the polymerase chain reaction and inserted into the expression vectors λgt11 and pGEX-3X. Both γ-galactosidase (LacZ) and glutathione-S-transferase (GST) fusion proteins containing the γ2IL were purified, and a rabbit antibody to the LacZ–γ2IL was made. The antibody reacted with the γ2IL of both LacZ and GST fusion proteins and immunoprecipitated the GABAAR/ benzodiazepine receptor (GABAAR/BZDR) from bovine and rat brain. The antibody reacted in affinity-purified GABAAR/BZDR immunoblots with a wide peptide band of 44,000–49,000 Mr. Immunoprecipitation studies with the anti-γ2IL antibody suggest that in the cerebral cortex, 87% of the GABAARs with high affinity for benzodiazepines and 70% of the GABAARs with high affinity for muscimol contain at least a γ subunit, probably a γ2. These results indicate that there are [3H]muscimol binding GABAARs that do not bind [3H]flunitrazepam with high affinity. Immunoprecipitations with this and other anti-GABAAR/BZDR antibodies indicate that the most abundant combination of GABAAR subunits in the cerebral cortex involves α1, γ2 (or other γ), and β2 and/or β3 subunits. These subunits coexist in 〉60% of the GABAAR/BZDRs in the cerebral cortex. The results also show that a considerable proportion (20–25%) of the cerebellar GABAAR/BZDRs is clonazepam insensitive. At least 74% of these cerebellar receptors, which likely contain α6, also contain γ2 (or other γ) subunit(s). The α1 and β2 or β3 subunits are also frequently associated with γ2 (or other γ) and α6 in these cerebellar receptors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1993.tb03243.x
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